1. Field of the Invention
The present invention relates generally to resettable circuit interrupting devices and systems and more particularly to a new improved ground fault circuit interrupter (GFCI) protected receptacle having means to selectively prevent a plug from being inserted therein.
2. Description of the Related Art
Many electrical wiring devices have a line side which is connectable to an electrical power supply, a load side which is connectable to one or more loads and at least one conductive path between the line and load sides. Electrical connections to wires supplying electrical power or to wires conducting electricity to one or more loads can be at the line side and load side connections of a wiring device. The electrical wiring device industry has witnessed an increasing call for circuit breaking devices or systems which are designed to interrupt power to a load, such as household appliances, consumer electrical products, branch circuits, etc. In particular, electrical codes require electrical circuits in home bathrooms, in kitchens and outdoor convenience outlets to be equipped with ground fault circuit interrupters (GFCI). Presently available GFCI devices, such as the device described in commonly owned U.S. Pat. No. 4,595,894 ('894), use an electrically activated trip mechanism to mechanically break an electrical connection between the line side and the load side. Such devices are resettable by depressing a reset button after they have been tripped by, for example, detection of a ground fault. In the device disclosed in the '894 patent, the trip mechanism used to cause the mechanical breaking of the circuit, i.e., the conductive path between the line and load sides, includes a solenoid or trip coil. A test button located in the face of the GFCI is used to test the trip mechanism and circuitry is provided to sense faults. A reset button located in the face of the GFCI is provided to reset the electrical connection between the line and load sides.
However, instances may arise where an abnormal condition such as a lightning strike may result not only in a surge of electricity which causes the device to trip, but can also cause the trip mechanism in the GFCI used to break the circuit to become non-operational. This condition can occur without the knowledge of the user. Under such circumstances an unknowing user, faced with a GFCI which has tripped, may press the reset button which, in turn, will cause the device with an inoperative trip mechanism to be reset without the ground fault protection being available.
Further, an open neutral condition, which is defined in Underwriters Laboratories (UL) Standard PAG 943A, may exist with the electrical wires supplying electrical power to such GFCI devices. If an open neutral condition exists with the neutral wire on the line (versus load) side of the GFCI device, an instance may arise where a current path is created from the phase (or hot) wire supplying power to the GFCI device through the load side of the device and a person to ground. In the event that an open neutral condition exists, a GFCI device which has tripped, may be reset even though the open neutral condition may remain.
Commonly owned U.S. Pat. No. 6,040,967, which is incorporated herein in its entirety by reference, describes a family of resettable circuit interrupting devices capable of locking out the reset portion of the device if the circuit interrupting portion is non-operational or if an open neutral condition exists. Circuit interrupting devices normally have a user accessible load side connection such as a GFCI protected receptacle in addition to line and load side connections such as binding screws. The user accessible load side connected receptacle can be used to connect an appliance such as a toaster or the like to electrical power supplied from the line side. The load side connection and the receptacle are typically electrically connected together. As noted, such devices are connected to external wiring so that line wires are connected to the line side connection and load side wires are connected to the load side connection. However, instances may occur where the circuit interrupting device is improperly connected to the external wires so that the load wires are connected to the line side connection and the line wires are connected to the load connection. The inadvertent switching of conductors between the line and load terminals, which is known as reverse wiring, leaves the plug engaging receptacle contacts in the face of a GFCI unprotected. Such miswiring is prevalent in new construction where power is not yet provided to the branch circuits and the electrician/installer has difficulty in distinguishing between the line side conductors and the load side conductors. In the event the circuit interrupting device is reverse wired, the user accessible load connection may not be protected, even if fault protection to the load side connection remains.
A resettable circuit interrupting device, such as a GFCI device, that includes reverse wiring protection, and optionally an independent trip portion and/or a reset lockout portion disclosed in U.S. Pat. No. 6,246,558, ('558) assigned to the same assignee and incorporated herein by reference in its entirety provides a solution to the problem of reverse wiring. In '558, the reverse wiring protection operates at both the line and load sides of the device to provide fault protection if the line side wiring to the device is improperly connected to the load side. The trip portion operates independently of the circuit interrupting portion used to break the electrical continuity in one or more conductive paths in the device. The reset lockout portion prevents the reestablishing of electrical continuity of an open conductive path if the circuit interrupting portion is not operational or if an open neutral condition exists. While the breaking of the electrical circuit disclosed in '558 provides protection, a blocking means which prevents a user from inserting a plug into the receptacle of a GFCI in a fault state is desired as it will provide added safety.